Agnosia Health Article

Auditory agnosia

Auditory agnosics fail to ascribe values to verbal or non-verbal sounds. Individuals with pure word deafness have intact hearing, but are unable to understand the spoken word, typically the result of bilateral trauma to the temporal cortico-subcortical regions of the brain. Nonverbal auditory agnosics fail to associate sounds with specific objects or events, such as a dog's bark or the slamming of a door. In these patients, the lesions tend to locate to the right hemisphere.

Tactile agnosia

Tactile agnosia, also called astereognosis, is often difficult to recognize as we rarely identify objects solely by feel. Information about the object, including its weight, size, and texture are not given any value. Lesions in the somatosensory cortex are thought to be responsible for the condition.

BOOKS

"Agnosia," Section 14, Chapter 169. In The Merck Manual of Diagnosis and Therapy, Mark H. Beers, and Robert Berkow, eds. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Farah, M. J. Disorders of Object Recognition and What They Tell us About Normal Vision, 2nd edition. Cambridge, MA: The MIT Press, 1995.

Freinberg, T. E. and M. J. Farah. "Cognitive-Motor Disorders, Apraxias, and Agnosias." In Neurology in Clinical Practice: Principles of Diagnosis and Management, 3rd edition, W. G. Bradley, R. B. Daroff, G. M. Fenichel, et al., eds. Boston, MA: Butterworth Heinemann, 2000.

PERIODICALS

Barton, J. J. S. "Disorders of face perception and recognition." Neurologic Clinics of North America 21 (2003): 521–548.

Hodgson, T. L., and C. Kennard. "Disorders of higher visual function and hemi-spatial neglect." Current Opinion in Neurology 13 (2000): 7–12.

Riddoch, M. J. and G. W. Humphreys. "Visual agnosia." Neurologic Clinics of North America 21 (May 2003): 501–520.

WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Agnosia Information Page. <http://www.ninds.nih.gov/health_and_medical/disorders/agnosia.htm>.

ORGANIZATIONS

National Eye Institute (NEI), National Institutes of Health. Bldg. 31, Rm. 6A32, Bethesda, MD 20892-2510. (301) 496-52482 or (800) 869-2020. 020@b31.nei.nih.gov. <http://www.nei.nih.gov>.

National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health. Bldg. 31, Rm. 3C35, Bethesda, MD 20892-2320, (301) 496-7243. nidcdinfo@nidcd.nih.gov. <http://www.nidcd.nih.gov>.

National Organization for Rare Disorders (NORD). P.O. Box 1968 (55 Kenosia Avenue), Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-NORD (6673); Fax: (203) 798-2291. orphan@rarediseases.org. <http://www.rarediseases.org>.

Hannah M. Hoag, MSc